The IEEE-1394 standard describes a network, which has network nodes and offers a serial bus connection between different devices, that has a high data-transmission rate. Such a network may also be known by the name of FireWire or iLink. The network may be made up of network nodes, which have one or more network-node outputs. The network nodes may be contained in devices, such as a radio, monitor, CD player, etc. Additional network nodes may be connected to network-node inputs and outputs.
The superordinate node of a network may be referred to as a root. Any node may become the root. In the topology, two nodes may have a child and parent relationship to each other, i.e. the superordinate node may be designated as a parent, and the subordinate node may be designated as a child. Therefore, a node may simultaneously be the parent of one node and the child of another node.
Network nodes that are only connected to one additional network node may be referred to as terminal nodes. Network nodes having two or more network nodes connected may be designated as branch nodes.
The network forming the basis of the present invention may be designed to independently configure itself without a host processor, the determination of the network topology, i.e. the configuration of the network, being carried out after the network is reset. A reset of the network may be initiated when, for example, a device or network node is removed from the network or an additional device or network node is added to the network. The configuration of a network may be carried out in three steps:
1. bus initialization:
The bus initialization may be triggered by a reset command, the individual network nodes transmitting the reset signal to the other network nodes. All information regarding the previous network topology may be deleted in the network nodes, and the network nodes may be shifted into the initialization state.
2. branch identification:
During the branch identification, the topology of the network may be detected, and the relationship of the network nodes to each other may be identified. The independent identification of the network nodes as parent and child with respect to each other may allow a root network node to be defined as a starting node, which may assume the bus management or network management.
3. self-identification:
To manage the network, the network topology and the physical characteristics of the network nodes may need to be known. To this end, the network nodes may transmit physical characteristics in a self-ID packet during self-identification. The transmission of the data regarding the individual network nodes may occur in the order of the topology configuration of the network, so that the position of the network nodes in the network may be identified. The root network node may store the number of network nodes connected and their self-ID packet inside the topology map. The network topology, network-node number phy_id, and the physical characteristics of the network nodes connected may be extracted with the aid of the topology map.
A register memory, in which a network-node identification number or device identification number and further information regarding the network or the device may be stored, may be provided in each network node for the network configuration. Each device or each network node may be provided with an unequivocal identification of the manufacturer, vendor ID, which may be likewise stored in the register memory. In addition, a unique number (chip ID) of the integrated circuit, in which the hardware and software for producing the network node is incorporated, may be stored in the register memory. The physical characteristics of the network node and the states of the corresponding network outputs (ports) may be input in the register memory as additional information items. The characteristics may include, for example, speed (sp=speed), delay time (del=delay), pause interval (gap-cnt=gap-count), voltage class (pwr=power class), etc.
The root network node may be provided with a register memory for storing the so-called network-topology map, which may include the number of network nodes connected and the information transmitted from the network nodes to the root network nodes regarding the characteristics of the specific network nodes (self-ID packets). In this connection, each network node may be assigned a network-node number phy_id by the root network node. The information items (self-ID packet) transmitted by a network node to the root network node may include network-node number (phy_id), pause number (gap-cnt), speed (sp), delay (del), voltage class (pwr), as well as additional information.
Data may be transmitted by a network node to another network node.
A serial bus may be defined by the IEEE-1394 standard. Examples of similar buses include MOST, HiQoS, CAN, Universal Serial Bus (USB), etc., which may likewise represent a network of the species.
In networks, a reset of the network may be carried out after the network topology is changed, e.g. by adding or removing devices, and the information regarding the previous network topology may be lost. This may be especially problematic when external devices are added or the network is manipulated.